An uncommon disease in which a substance called amyloid, composed of fibrous protein, accumulates in tissues and organs, including the liver, kidneys, tongue, spleen, and heart. Amyloidosis may occur for no known reason, in which case it is called primary; more commonly, it is a complication of some other disease, and in such cases it is called secondary. Conditions that may lead to amyloidosis include multiple myeloma (a cancer of bone marrow), rheumatoid arthritis, tuberculosis, and some other longstanding infections, such as chronic osteomyelitis. The symptoms of amyloidosis vary, depending on the organs affected and the duration of the condition. Deposits of amyloid in the kidneys may cause kidney failure, which may be fatal. There is no treatment, but secondary amyloidosis can be halted if the underlying disorder is treated.


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